The UK’s The Guardian reported that the report authors say, “urgent and unprecedented changes are needed to reach the target, which they say is affordable and feasible although it lies at the most ambitious end of the Paris Agreement pledge to keep temperatures between 1.5C and 2C.”

The Intergovernmental Panel on Climate Change climate forecasts were wrong from their earliest reports in 1990. They were so inaccurate that they stopped calling them forecasts and made three “projections”: low, medium, and high. Since then, even their “low” scenario projections were wrong.

The Intergovernmental Panel on Climate Change created an illusion of certainty about their science, and therefore their forecasts. They let people think that they study all causes of climate change when they only look at human-caused change. That is impossible unless you know and understand total climate change and the mechanisms, and we don’t. It allowed them to ignore all non-human causes of change, including the Sun.

One of the reasons the Intergovernmental Panel on Climate Change gets away with this is that almost no one reads the underlying science reports. Indeed, the “Final Government Draft” of the underlying science report, which appears on the IPCC Web site, even cautions the reader, “Do Not Cite, Quote or Distribute.”

Partly for this reason, but mainly because the underlying science reports are so complicated, media and politicians rely instead on the SR15 Summary for Policymakers (SPM). This document is written mostly by government representatives and also has to be approved by them. The SPM is consequently a highly political document that fulfils policy objectives of the member governments and typically does not properly reflect uncertainties in the underlying science.

Writing in 2002 about the SPM of Working Group I of the IPCC Third Assessment Report, IPCC Reviewer and independent analyst David Wojick explained the sort of problems typical of Intergovernmental Panel on Climate Change summary reports:

What is systematically omitted from the Summary for Policymakers are precisely the uncertainties and positive counter evidence that might negate the human interference theory. Instead of assessing these objections, the Summary confidently asserts just those findings that support its case. In short, this is advocacy, not assessment.

Having tracked the evolution of SR15 for the past six months, Mr. Wojick says that this is exactly what has happened on this latest report as well.

The Intergovernmental Panel on Climate Change procedures allow government representatives to ultimately control the underlying science reports as well by specifying that changes to the science reports may be made even after they have been approved “to ensure consistency with the Summary for Policymakers.” In fact, when releasing the Final Government Draft of the underlying science report for SR15, the IPCC specifies that it is “Subject to correction, copy-editing, layout and ‘trickleback.’” Trickleback is adjustments to the text of the science report to assure that it conforms with the approved SPM. Mr. Wojick laughs, pointing out that “trickleback” begins with “trick.”

Although the Intergovernmental Panel on Climate Change asserts in the SR15 trickleback report that “These changes do not alter any substantive findings of the final draft of the underlying report,” considering the contrast between past IPCC SPMs and the underlying science reports, this is difficult to believe. Regardless, the complexity of this process ensures that, like the science report itself, virtually no one reads the trickleback document to see where the science report has been changed.

The scientific section of the IPCC Third Assessment Report illustrates how little they actually know about climate futures:

In climate research and modelling, we should recognize that we are dealing with a coupled non-linear chaotic system, and therefore that the long-term prediction of future climate states is not possible.

The supposed threat is a 1.5 to 2C increase, but global temperatures were higher than today by at least that much for most of the last 10,000 years. Yet polar bears and the world survived.

No one should take the new IPCC climate report seriously.

• Tim Ball is an environmental consultant and former climatology professor at the University of Winnipeg in Manitoba. Tom Harris is executive director of the Ottawa, Canada-based International Climate Science Coalition.